Chapter 10, Problem 10.64P

Interpretation Introduction

(a)

Interpretation:

The wt% of the tungsten fibers present in the given composite is to be calculated.

Concept Introduction:

The formula to convert vol% to wt% using density $\left(\rho \right)$ is:

  ${\left(\text{wt\%}\right)}_1=\frac{\left[{\left(\text{vol\%}\right)}_1\times {\rho }_1\right]}{\left[{\left(\text{vol\%}\right)}_1\times {\rho }_1+{\left(\text{vol\%}\right)}_2\times {\rho }_2\right]}\times 100$   ...... (4)

Interpretation Introduction

(b)

Interpretation:

The effect of heating the given composite of Nb and W to ${2600}^{\circ }\text{C}$ and being held there for several years is to be explained.

Concept Introduction:

A property of a substance known as solute whether it is solid, liquid, or gaseous to get dissolved in the solid, liquid or gaseous solvent is known as solubility.

When two or more solid chemical substances are dissolved in each other and only one phase appears after mixing irrespective of any concentration of the solute in the solvent, then there is unlimited solid solubility.

Hume-Rothery rules are the conditions which are to be satisfied to attain unlimited solid solubility. These rules are stated as:

1. The size of the atoms or the ions involved should be similar to minimize the lattice strain. This means that there should not be more than $15\%$ difference in the atomic radius to avoid the deviations caused in the interatomic spacing.

2. The crystal structure of both the materials should be same to avoid different structure caused due to the transition from one phase to another phase at some point.

3. The difference in the valency of the ions causes the formation of compounds rather than solutions. Thus, the valence of the ions must be same.

4. The significant difference in the electronegativity (affinity for electrons) caused the compound formation rather than solutions. Therefore, the electronegativity of atoms must be approximately same.